Power semiconductor modules are used in inverters, uninterruptive power supplies, machine tools, industrial robots, and such apparatuses in the form of packages, independent from these industrial apparatuses. Such a power semiconductor module houses therein one or more semiconductor chips insulated gate bipolar transistors (hereinafter referred to as “IGBTs”) and such power semiconductor devices constituting the power converter circuit. The power semiconductor module is mounted on a predetermined control circuit board for controlling any of the apparatuses described above. See for instance JP 2002-50722 A.
The following describes such a power semiconductor module that houses a plurality of semiconductor chips. Typically, the power semiconductor module mounts the semiconductor chips on an insulating circuit board by soldering. The power semiconductor module has the leads connected to the control circuit board and the semiconductor chips by wire bonding using metal wires. Then, the power semiconductor module incorporating therein the semiconductor chips, mounted on the insulating circuit board and connected to the leads by wire bonding, is packaged by molding in a resin casing. A radiator plane arranged on the side opposite to the side of the resin casing, on which outer leads are mounted, is in contact with a cooling fin so that the heat generated in the power semiconductor devices can be dissipated to the outside.
Since the cross sectional area of the metal wires connecting the outer leads and the semiconductor chips in the power semiconductor module described above is relatively small, the module is limited in its current capacity. While a thick metal wire can improve the current capacity, it is difficult to bond the thick metal wire by ultrasonic bonding or by welding.
The manufacturing process for manufacturing the power semiconductor module includes soldering the semiconductor chip to the insulating circuit board and connecting the semiconductor chips and the outer lead portions by wire bonding. The metal wire bonding is conducted wire by wire. Since from 200 to 500 metal wires are typically used for manufacturing the power semiconductor module, it takes a long time to bond the metal wires.
Accordingly, there remains a need to provide a power semiconductor module that is manufactured more efficiently. The present invention addresses this need.